Apparatus for grinding curved blades



Feb. 14,1939. -H W BARNARD 1 2,147,079

APPARATUS FOR GRINDING CURVED BLADES Filed Jan. 29, 1938 Patented Feb;14, 1939 UNITED STATES PATENT OFFICE 2,147,079 APPARATUS FOR. GRINDINGCURVED BLADES Harlin W. Barnard, Olean, N. Y. 7 Application January 29,1938, Serial No. 187,739

3Claims. (01. 51-100) This invention relates to means for grindingcutting blades and its principabobiect is to pro-- vide means ofuniformally beveling the surface of the blade terminating in the cuttingedge, of 5 blades having compound edge curvature, that is to say, bladeshaving difierent portions of their edges curved on different centers ofcurvature.

The primary object of this invention is to provide means for grinding aknife blade with a bevel edge wherein the line of bevel will besubstantially concentric with the varying curvature of the cutting edgeby the use of a specially designed blade holder adapted to be moved infixed relation to the grinding means and bringing all points 15 of theedge of a compound curved blade progressively into bevel formingpositions, in relation to the grinding means whereby a bladehaving anedge formed in two or more curves, a curve of short radius near theblade point, merging into *a curve, or curves of long radii in the bodyof the blade, will be provided. with a uniform bevel throughout itscutting edge.

The apparatus herein shown comprises as its principal units, a bladeholder with a controlling factor for accurately determining the path andposition of the blade holder at various points in its movement withrelation to the grinding and sharpening means.

These and other features of the invention will be more clearlyunderstood from the following description thereof, together with theaccompanying drawing, in which- Fig. 1 is a view in side elevation ofthe blade holder assembled with a knife blade positioned therein.

' Fig. 2 is a plan view of the outline of a blade blank adapted to bepositioned in the blade holder.

Fig. 3 is a plan view of one of the pair of side plates forming theblade holder.

Fig. 41s a plan view of the bottom element of the blade holder adaptedto be positioned intermediate of the side plates in theblade holder I Yassembly.

Fi 5 shows a cross section view of the blade holder and blade shown inFig. 1 on the line 5-5.

Fig. 6 shows a cross section view of the blade holder and blade on theline 6-8. s

Fig. 7 is a view in-side elevation of the blade holder with a bladepositioned therein preparatory to the grinding operation.

Fig. 8 is an end view of the companion grinding disk with the bladeholder with blade therein positioned for the grinding operation.

In the drawing Figs. 1 to 4 inclusive, are shown 05 the component partsof the blade holder assembly 5, wherein l0 designates the bottom part ofthe blade holder, ll designates one of the companion side plates adaptedto be riveted together with the bottom element l0 interposedtherebetween to form a troughinto which the blade is 5 positioned.

The bottom element I0 has a definitely shaped outline on both edges, theobject of which will be more fully explained.

As shown in Fig. 2 the knife blade blank [2 10 is formed with a contourat its back edge providing shoulders formed at I and 2. This contourconforms to the shape of the blade contacting edge of the bottom elementIll shown in Fig. 4. As the back of the blade blank l2 rests upon thebottom element ill, the shoulders I and Zwill maintain the blade blankl2 against lateral movement within the blade holder 5 by the shoulders Iand 2 registering in the depressions 3 and 4 of the bottom element l0.

Further resistance to lateral movement of the blade 12 is provided bythe extension l3 of the member l0 which engages the end of the tangportion of the blade .To afford suitable grinding means there isprovided, as shown in Fig. 8, a pair of companion grinding disks l5 andI5 formed of any suitable abrasive medium, mounted upon suitable arbors,rotatively mounted in bearings well known in the art (not shown) thearbor of the one companion disk l5 being held in a fixed position, andthe arbor of the other companion disk I 5, being adapted to move in ahorizontal plane toward and away from the companion disk l5 mounted onthe fixed positioned arbor, by means well known Y in the art (notshown).

Positioned in a vertical plane on a line between the peripheries of thecompanion disks l5 and I5 is an adjustable standard or post id, uponwhich the back of the knife blade holder I0 is adapted to contact in itsmovement duringthe grinding operation.

The form of the blade holder element l0 forms an important part of thisinvention, as will be appreciated as the grinding operation is morefully described as follows:

With the blade blank l2, positioned inthe blade holder 5, as shown inFig. 1 the blade holder with the blade therein is placed in positionbetween the grinding disks l5 and IS with the back member In of theblade holder resting upon the support H as shown in Figs. 7 and 8.

With the edge of theblade blank l2 interposed between the companiondisks l5 and I5 in a grinding contact therewith, the .blade holderelement l resting upon the supportingelement M, which so guides thetopedge of the blade blank 12, with respect to its relation with thegrinding disks that the line of bevel shown as It in Fig.1 will besubstantially parallel with the outline of the bottom edge of elementIt! contacting the top of the supporting element ll.

It will be obvious that other forms of curved surface elements III maybe provided to form other contours of the line of bevel as well as thecontour of the cutting edge of blades of other shapes.

In the movement of the *blade holder as shown in Fig. 7 from right toleft, as the element l0 moves on top of the supporting element It, thedeclining curve formed in the terminal of the elem nt l0 willcause the.blade holder 5 to change ts path on movement to apply the cutting edgeof the knife blade to the abrasive means along a line of curvaturedetermined by the arc of the curve formed in the terminal of the element"I. It will be obvious from the foregoing description of its operation,that with my improved apparatus, knife blades having curved cuttingedges may be readily ground by inexperienced operators to produce a lineof bevel extending back from the cutting edge, a predetermined distanceand concentric with the cutting edge.

It will be obvious to those skilled in the art, that a uniform bevelwillbe formed on both sides of the blade in the one operation.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patcut is: v

1. In a grinder for knives having compound 2,147,079 '5, is movedhorizontally with the blade holder curved cutting edges, the combinationwith a pair of grinding wheels, a support intermediate thereof, aportable blade holder associated with said support and adapted forlateral movement thereon with its support contacting surface formed in acompound curve whereby successive portions of the curved cutting edge ofthe knife may be selectively applied to the grinding wheels during alateral movement of the blade holder.

2. In a grinding device for knives having compound curved cutting edges,the combination with a frame of a. pair of grinding wheels mounted foradjustable relation therein, a support intermediate of said wheels, aportable blade holder associated with said support and adapted for lateral movement thereon having its support contacting. surface formed in acompound curve whereby in its lateral movement, successive portions ofthe compound curved cutting edge of the knife may be selectively appliedto the grinding wheels.

3. In a grinder for knives having compound cutting edges, thecombination with a frame of a pair of grinding wheels mounted in saidframe to be moved in adjustable relation to each other, and adjustablesupport intermediate of said wheels, 9. portable knife blade holderassociated with said support and adapted for lateral movement thereonformed with its contacting 'surface in a compound curve whereby in itslateral movement, successive portions of the compound curved cuttingedge of the knife may be selec tlvely applied to .both grinding wheelsduring the lateral movement of the blade holder.

. HARLIN W. BARNARD

